Speech processing techniques have been developed, and a speech translation apparatus, in which an input of a first language is translated into a second language and an output of the second language is obtained, has been achieved. The format of input and output are texts or sounds, depending on applications. However, the basic technique of translating a person's speech is commonly used in the applications.
The speech translation technique can be applied to displaying subtitles of translated languages, or speech output of translated languages in a meeting or a lecture. One example of a speech translation technique is a subtitling system for conferencing.